Estimating extreme heat event over New Delhi Region, India using Satellite Data

On May 26, 2024, Delhi experienced an extreme heat event, with temperatures soaring to record-breaking levels, exceeding 52°C, which was later revised to 46°C (114.8°F) by the India Meteorological Department.Amidst the controversy surrounding sensor failures, this study examines land surface temperature (LST) in Delhi using Landsat 9 OLI and MODIS Aqua data, focusing on the extreme heat event of May 26, 2024. This date was selected due to anticipated extreme heat and the availability of data. Satellite observations revealed temperatures as high as 56°C, with distinct spatial variations across Delhi. The western region recorded the highest temperatures, while the eastern region, influenced by the Yamuna River, exhibited cooler conditions. Emissivity values from Landsat (0.970–0.984) and MODIS (0.973–0.987) were analyzed, showing a strong correlation with surface temperatures: lower emissivity values corresponded to greener areas and lower temperatures, whereas higher values were linked to elevated temperatures. The study highlights the impact of surface characteristics on thermal behavior and underscores the role of urban heat islands (UHIs), particularly in northwestern Delhi. These UHIs, driven by industrial activity, dense settlements, and low-albedo materials, resulted in 2–4°C temperature differences between urban and rural areas, posing health risks to vulnerable populations. Mitigation strategies such as expanding green spaces and relocating high-emission industries are recommended to alleviate these risks. Despite the absence of field data, global studies validating Landsat and MODIS-derived LST support the accuracy of this study’s findings. Thus, the spatial pattern of LST remains reliable even with minor errors ranging from 1 to 2 °C. The study will help for strategic planning and mitigation measures to address extreme heat events in urban areas.